Validation of static residual strength analyses of fiber composite bonded joints
Topic(s) : Special Sessions
Co-authors :
Patrick Adrian MAKIELA (GERMANY), Oliver VOELKERINK (GERMANY), Jens KOSMANN (GERMANY), Martin Johannes SCHOLLERER (GERMANY), Dirk HOLZHÜTER , Christian HÜHNE (GERMANY)Abstract :
Safety-critical applications, such as adhesive bonds of fiber-reinforced composites in aircraft structures, face stringent regulations imposed by certification authorities. Meeting these regulations necessitates that adhesive bonds demonstrate damage tolerance to mechanical stresses incurred during operation or production. Currently, the impact of damages on static strength remains unclear, impeding the accurate prediction of residual strength for a save prediction. While validated material models of fiber-reinforced composites and modeling strategies exist for predicting static strength in undamaged adhesive bonds through numerical simulations, there is a lack of methods to validate models with pre-existing damages resulting from impacts or fatigue.
To address this gap, methodologies for validating models with pre-existing damages must fulfill several criteria. These methodologies need to be reproducible, with damages clearly defined, and controlled. Moreover, they must prevent error propagation, particularly concerning the initiation of damages and their numerical simulation.
The central research questions revolve around the applicability of validated modeling strategies for static strength in undamaged specimens to those with pre-existing damage. Additionally, the study seeks to identify suitable validation methods for residual strength of adhesive joints with pre-existing damages.
To tackle these questions, the chosen approach involves extending validated modeling strategies and material models to more complex specimens featuring artificial disbond and artificial interlaminar damages as they represent two primary damage mechanisms of pre-damaged bonded joints of fiber-reinforced composites. The test specimens for an experimental study are fabricated by introducing release films to represent the artificial damages, as this is easily reproducible. Advanced strategies and material models based on previous works are employed to model these specimens, aiming to achieve a certain accuracy of predictions. The study focuses on comparing the stiffness, strength, and failure modes between the numerical study and experimental results.
Through this study, it is possible to assess whether the application of existing simulation strategies to specimens with pre-existing damage is feasible without further adjustments. Additionally, robust validation techniques are proposed, which are crucial for the reliability of damage tolerance analyses in adhesive joints, particularly in aviation applications.
To address this gap, methodologies for validating models with pre-existing damages must fulfill several criteria. These methodologies need to be reproducible, with damages clearly defined, and controlled. Moreover, they must prevent error propagation, particularly concerning the initiation of damages and their numerical simulation.
The central research questions revolve around the applicability of validated modeling strategies for static strength in undamaged specimens to those with pre-existing damage. Additionally, the study seeks to identify suitable validation methods for residual strength of adhesive joints with pre-existing damages.
To tackle these questions, the chosen approach involves extending validated modeling strategies and material models to more complex specimens featuring artificial disbond and artificial interlaminar damages as they represent two primary damage mechanisms of pre-damaged bonded joints of fiber-reinforced composites. The test specimens for an experimental study are fabricated by introducing release films to represent the artificial damages, as this is easily reproducible. Advanced strategies and material models based on previous works are employed to model these specimens, aiming to achieve a certain accuracy of predictions. The study focuses on comparing the stiffness, strength, and failure modes between the numerical study and experimental results.
Through this study, it is possible to assess whether the application of existing simulation strategies to specimens with pre-existing damage is feasible without further adjustments. Additionally, robust validation techniques are proposed, which are crucial for the reliability of damage tolerance analyses in adhesive joints, particularly in aviation applications.